AGU Dispatches: Final Day and Final Thoughts

Unless you are presenting, the final day of a 5 day-conference can be a test of your intellectual fortitude: it can be tough to force your tired and stuffed-with-cool-new-science brain to take an interest in any more talks or posters. Still, it behooves us all to try, if only because you never know when it might be you who is giving one of the presentations in the Friday afternoon slot (as yours truly did last year), so the Golden Rule applies.

And thus it was that not too long after the 8am start, your intrepid blogger was installed in a session on continental rifting, with a focus on the Midcontinental Rift, a 1.1 billion year-old lava-filled hole in the ground which appropriately, if rather generically, dominates the geology (and gravity signature) of the US Midwest. It’s such a huge amount of lava, that it’s hard to understand why it ‘failed’ (in the sense that it didn’t transition to full oceanic spreading). But it does drive home the fact that the contribution of rifting processes to the growth of continental crust is somewhat under-appreciated, as Margaret Benoit rather astutely pointed out in the session. Her talk – which demonstrated how large amounts of basalt added to the continental crust in the Neoproterozoic was a major influence on the shape of the Appalachian mountain belt hundreds of millions of years later – was extremely interesting, as was Nick Swanson-Hyell’s contribution, which was an update of his paleomagnetic analysis of the lavas where they are exposed around Lake Superior, which I’ve written about before. It still seems that during eruption of the rift basalts Laurentia was moving rather faster than anyone is comfortable with, which also probably rules out the idea that the rift magmatism was fuelled by a mantle plume.

I then nipped across the way to a more seismology-focused session, where Nicholas van der Elst was the latest person to grapple with the question of whether great earthquakes can trigger other great earthquakes elsewhere in the world. As he pointed out, the recent cluster of extremely damaging earthquakes starting in 2004 is of more than academic interest: most of the people who have died due to earthquakes in living memory have died in the last seven years. Van der Elst’s analysis suggests that despite the recent carnage, there is no evidence for the earlier quakes such as the 2004 Sumatra quake triggering later ones, such as last year’s Tohuku quake (take that, Simon Winchester), although it should be noted that he was only examining one possible triggering mechanism, where the earlier great earthquake induced an increase in the rate of background seismicity in the area around the later great earthquake, leading to a “triggering cascade”.

After that I spent the time between lunch and shopping excursions mainly wandering the poster hall. As is often the case, if you wander with an open mind you can come across some real scientific gems in unexpected places, such as some nice constraints on the tectonic history of the Caribbean from basalt geochemistry, or a cool new type of model for continental deformation that gets around the trade-offs between viscous sheet and block models by kind of doing both.

But eventually, it was time to bid farewell to the Moscone Centre and head back to the real world, where there is a lot of work and cogitation between you and the cool new science, and other rather more urgent demands on your time (like undergrads wanting lectures and grades) to boot. Still, I’ve had a great week, and hopefully some of the thoughts and ideas that have been planted in my brain will bear enough fruit to bring me back next year to be inspired anew. And who knows, maybe the 2013 AGU meeting app will also not force you to navigate between multiple screens to find the time, author and location of a talk, and will recognise that you can attend more than one poster session at a time.

I hope that these dispatches have at least given you a flavour of the size and the excitement, and the concentrated cool new science, that is on offer at a big scientific conference at AGU. Now, sleep…